Mask



FIG. 1 is a front elevation view of a mask showing my new design;

FIG. 2 is a back elevation view thereof;

FIG. 3 is a left side elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a front perspective view thereof; and,

FIG. 8 is a rear perspective view thereof. 

CLAIM The ornamental design for a mask, as shown and described. 